Paola Tamburini

Moving from laboratory to real life conditions: Influence on the assessment of variability and stability of gait

The availability of wearable sensors allows shifting gait analysis from the traditional laboratory settings, to daily life conditions. However, limited knowledge is available about whether alterations associated to different testing environment (e.g. indoor or outdoor) and walking protocols (e.g. free or controlled), result from actual differences in the motor behaviour of the tested subjects or from the sensitivity to these changes of the indexes adopted for the assessment. In this context, it was hypothesized that testing environment and walking protocols would not modify motor control stability in the gait of young healthy adults, who have a mature and structured gait pattern, but rather the variability of their motor pattern. To test this hypothesis, data from trunk and shank inertial sensors were collected from 19 young healthy participants during four walking tasks in different environments (indoor and outdoor) and in both controlled (i.e. following a predefined straight path) and free conditions. Results confirmed what hypothesized: variability indexes (Standard deviation, Coefficient of variation and Poincaré plots) were significantly influenced by both environment and walking conditions. Stability indexes (Harmonic ratio, Short term Lyapunov exponents, Recurrence quantification analysis and Sample entropy), on the contrary, did not highlight any change in the motor control. In conclusion, this study highlighted an influence of environment and testing condition on the assessment of specific characteristics of gait (i.e. variability and stability). In particular, for young healthy adults, both environment and testing conditions affect gait variability indexes, whereas neither affect gait stability indexes.

Towards an objective assessment of motor function in sub-acute stroke patients: Relationship between clinical rating scales and instrumental gait stability indexes

The assessment of walking function alterations is a key issue to design effective rehabilitative interventions in sub-acute stroke patients. Nevertheless, the objective quantification of these alterations remains a challenge. Clinical rating scales are commonly used in clinical practice, but have been proven prone to errors associated to the evaluator subjective perception. On the other hand, instrumental measurement of trunk acceleration can be exploited for an objective quantitative characterization of gait function, but it is not applied in routine clinical practice, because the resulting quantitative indexes have not been related to the clinically information, conventionally provided by the rating scales. To overcome this limitation, the relationship between the indexes, in specific clinical conditions, and rating scale must be better investigated, to support their exploitability in the clinical practice as a fast and reliable screening tool. Thirty-one sub-acute stroke patients (17 with and 14 without cane) participated in the study. All were assessed with 6 rating scales (MI, TCT, MRI, FAC, WHS, CIRS) and 2 functional tests (2MWT and TUG). Sample Entropy (SEN) and Recurrence Quantification Analysis (RQA) in AP, ML and V directions were calculated over 2MWT and walking section of TUG. The influence of assessment task and cane was analysed, as well as correlation of SEN and RQA indexes with clinical rating scales. SEN and RQA on the medio-lateral plane resulted influenced by the use of the cane, while the correlations between indexes and clinical scales showed that SEN and RQA for antero-posterior direction correlate positively with WHS.

Nonlinear analysis of human movement dynamics offer new insights in the development of motor control during childhood.

When aiming at assessing motor control development, natural walking (NW) and tandem walking (TW) are two locomotor tasks that allow analysing different characteristics of motor control performance. NW is the reference locomotor task, expected to become more and more automatic with age. TW is a non-paradigmatic task used in clinics to highlight eventual impairments and to evaluate how a child deals with a new challenging motor experience. This work aims at investigating motor development in school-aged children, by assessing quantitatively their performance during TW and NW. 80 children (6-10 years) participated in the study. Trunk acceleration data and nonlinear measures (recurrence quantification analysis, RQA, and multiscale entropy, MSE) were used to characterize postural control ability and motor complexity. Results were analysed with respect to age and standard clinical assessment of TW (number of correct consecutive steps), by means of Pearson correlation coefficients. RQA and MSE allowed highlighting age-related changes in both postural control stability and motor complexity, while classic standard assessment of TW resulted uniformly distributed in the different age groups. Present results suggest this quantitative approach as relevant when assessing motor development in schoolchildren and complementary to standard clinical tests.

Fall Risk Monitoring: From Laboratory to Portable Device, Influence of Sampling Frequency

The understanding of locomotor stability is a critical issue in the assessment of subjects with high level of fall risk either pathological (e.g. stroke subjects) or elderly. Clinical assessment of fall risk is typically based on clinical rating scales; however, this approach heavily relies on the clinician’s subjective judgment. Instrumental stability and variability indexes of gait can represent a promising solution for the objective quantification of locomotor function and fall risk. Furthermore clusters of stability and variability indexes give important information about the clinical deficits of subjects that could be the causes of the fall risk.

Design of a Modular Small Dimensions Force Platform for Gait Analysis

Gait analysis of subjects with short and non-uniform gait is difficult using the common commercial force platforms. The present work consists in the design, based on finite element method (FEM) analysis, of a force platform of small dimensions (0.40x0.40 m) considering static and dynamic simulation of its behavior. The aim of this project is to improve, with a simple and low cost structure, the instrumentation available for the gait analysis of children and neurologic patients. The applicability of gait analysis to children and neurologic patients, improved the flexibility of force platforms without loosing the performance provided by traditional force platforms (e.g. for postural analysis)

Is There a Relationship between Clinical Rating Scales and Instrumental Gait Stability Measures

Clinical assessment of walking deficits in post-stroke patients is typically based on clinical rating scales. This approach is however highly dependent on the clinician’s subjective judgement. Objective tools for the quantification of locomotor function are needed, and instrumental measures of gait stability could represent a promising solution. The integration of the two approaches could lead to a more reliable quantification of locomotor deficits in post-stroke patients, and improving the understanding of the physiological correlate of gait stability measures. The aim of the present study was to assess the association between instrumental stability measures based on trunk accelerations during gait and clinical rating scales in a sample of post-acute stroke subjects.

DESIGN OF A NOVEL FORCE PLATFORM FOR GAIT ANALYSIS: FEM ANALYSIS

The gait analysis of subjects with short and non-uniform gait is difficult using the common commercial force platforms. The present work consists in the design, based on finite element method (FEM) analysis, of a force platform of two different dimensions (0.40 × 0.40 m and 0.80 × 0.40 m) considering static and dynamic simulation of their behavior. The aim of this project is to improve, with a simple, low cost and flexible structure, the instrumentation available for the gait analysis of children, neurologic patients and in general the most common clinical cases. The applicability of gait analysis to children, neurologic patients ECC can be improved by the flexibility of force platforms without losing the performance provided by traditional force platforms (e.g., for postural analysis).